The present invention relates to a photoelectric input apparatus for display systems, and more particularly to a photoelectric touch input apparatus adapted to be placed in front of the display surface of a display device such as a cathode ray tube, a liquid crystal display panel or the like.
Such a conventional photoelectric touch input apparatus as described above comprises a plurality of light-emitting elements arranged in a row along one side of a display surface on the front of a display device to generate a plurality of light beams in parallel spaced relationship in a common plane, a plurality of photosensitive elements arranged in a row along the opposite side of the display surface to receive the light beams from the light-emitting elements, a detecting circuit associated with the photosensitive elements to produce an output signal indicative of the position of an operator's finger or stylus when it interrupts one of the light beams, and switch means responsive to the output signal of the detecting circuit to switch over an indication or picture on the display surface to another indication or picture defined by the position of the operator's finger or stylus. If in use of the photoelectric input apparatus, more than one of the light beams is erroneously broken by an angled approach of the operator's finger or stylus, there will occur an error in identification of the position of the operator's finger or stylus, resulting in a false indication on the display surface.